package com.liang.servlet;

import sun.net.www.content.image.png;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URLEncoder;

public class FileServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1、	要获取下载文件的路径
        ServletContext context = this.getServletContext();
        String realPath = "C:\\Users\\35126\\Desktop\\java学习\\javaweb\\javaweb-02-servlet\\response\\src\\main\\resources\\猜猜呗.png";
        System.out.println("下载文件的路径"+realPath);
        //2、	下载的文件名是什么
        String fileName = realPath.substring(realPath.lastIndexOf("\\") + 1);
        //3、	想办法让浏览器能够支持下载我们需要的东西
        resp.setHeader("Content-disposition","attachment;filename"+ URLEncoder.encode(fileName,"UTF-8"));

        //4、	获取下载文件的输入流
        FileInputStream in = new FileInputStream(realPath);
        //5、	创建缓冲区
        int len = 0;
        byte[] buffer = new byte[1024];
        //6、	获取OutputStream对象
        ServletOutputStream out = resp.getOutputStream();
        //7、	将FileOutPutStream流写入到buffer缓冲区,使用OutPutStream将缓冲区中的数据输出到客户端
        while ((len=in.read(buffer))>0){
            out.write(buffer,0,len);
        }

        in.close();
        out.close();


    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}
